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Mirrors > Home > MPE Home > Th. List > fac3 | Structured version Visualization version GIF version |
Description: The factorial of 3. (Contributed by NM, 17-Mar-2005.) |
Ref | Expression |
---|---|
fac3 | ⊢ (!‘3) = 6 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-3 12300 | . . 3 ⊢ 3 = (2 + 1) | |
2 | 1 | fveq2i 6894 | . 2 ⊢ (!‘3) = (!‘(2 + 1)) |
3 | 2nn0 12513 | . . 3 ⊢ 2 ∈ ℕ0 | |
4 | facp1 14263 | . . 3 ⊢ (2 ∈ ℕ0 → (!‘(2 + 1)) = ((!‘2) · (2 + 1))) | |
5 | 3, 4 | ax-mp 5 | . 2 ⊢ (!‘(2 + 1)) = ((!‘2) · (2 + 1)) |
6 | fac2 14264 | . . . 4 ⊢ (!‘2) = 2 | |
7 | 2p1e3 12378 | . . . 4 ⊢ (2 + 1) = 3 | |
8 | 6, 7 | oveq12i 7426 | . . 3 ⊢ ((!‘2) · (2 + 1)) = (2 · 3) |
9 | 2cn 12311 | . . . 4 ⊢ 2 ∈ ℂ | |
10 | 3cn 12317 | . . . 4 ⊢ 3 ∈ ℂ | |
11 | 9, 10 | mulcomi 11246 | . . 3 ⊢ (2 · 3) = (3 · 2) |
12 | 3t2e6 12402 | . . 3 ⊢ (3 · 2) = 6 | |
13 | 8, 11, 12 | 3eqtri 2760 | . 2 ⊢ ((!‘2) · (2 + 1)) = 6 |
14 | 2, 5, 13 | 3eqtri 2760 | 1 ⊢ (!‘3) = 6 |
Colors of variables: wff setvar class |
Syntax hints: = wceq 1534 ∈ wcel 2099 ‘cfv 6542 (class class class)co 7414 1c1 11133 + caddc 11135 · cmul 11137 2c2 12291 3c3 12292 6c6 12295 ℕ0cn0 12496 !cfa 14258 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1790 ax-4 1804 ax-5 1906 ax-6 1964 ax-7 2004 ax-8 2101 ax-9 2109 ax-10 2130 ax-11 2147 ax-12 2167 ax-ext 2699 ax-sep 5293 ax-nul 5300 ax-pow 5359 ax-pr 5423 ax-un 7734 ax-cnex 11188 ax-resscn 11189 ax-1cn 11190 ax-icn 11191 ax-addcl 11192 ax-addrcl 11193 ax-mulcl 11194 ax-mulrcl 11195 ax-mulcom 11196 ax-addass 11197 ax-mulass 11198 ax-distr 11199 ax-i2m1 11200 ax-1ne0 11201 ax-1rid 11202 ax-rnegex 11203 ax-rrecex 11204 ax-cnre 11205 ax-pre-lttri 11206 ax-pre-lttrn 11207 ax-pre-ltadd 11208 ax-pre-mulgt0 11209 |
This theorem depends on definitions: df-bi 206 df-an 396 df-or 847 df-3or 1086 df-3an 1087 df-tru 1537 df-fal 1547 df-ex 1775 df-nf 1779 df-sb 2061 df-mo 2530 df-eu 2559 df-clab 2706 df-cleq 2720 df-clel 2806 df-nfc 2881 df-ne 2937 df-nel 3043 df-ral 3058 df-rex 3067 df-reu 3373 df-rab 3429 df-v 3472 df-sbc 3776 df-csb 3891 df-dif 3948 df-un 3950 df-in 3952 df-ss 3962 df-pss 3964 df-nul 4319 df-if 4525 df-pw 4600 df-sn 4625 df-pr 4627 df-op 4631 df-uni 4904 df-iun 4993 df-br 5143 df-opab 5205 df-mpt 5226 df-tr 5260 df-id 5570 df-eprel 5576 df-po 5584 df-so 5585 df-fr 5627 df-we 5629 df-xp 5678 df-rel 5679 df-cnv 5680 df-co 5681 df-dm 5682 df-rn 5683 df-res 5684 df-ima 5685 df-pred 6299 df-ord 6366 df-on 6367 df-lim 6368 df-suc 6369 df-iota 6494 df-fun 6544 df-fn 6545 df-f 6546 df-f1 6547 df-fo 6548 df-f1o 6549 df-fv 6550 df-riota 7370 df-ov 7417 df-oprab 7418 df-mpo 7419 df-om 7865 df-2nd 7988 df-frecs 8280 df-wrecs 8311 df-recs 8385 df-rdg 8424 df-er 8718 df-en 8958 df-dom 8959 df-sdom 8960 df-pnf 11274 df-mnf 11275 df-xr 11276 df-ltxr 11277 df-le 11278 df-sub 11470 df-neg 11471 df-nn 12237 df-2 12299 df-3 12300 df-4 12301 df-5 12302 df-6 12303 df-n0 12497 df-z 12583 df-uz 12847 df-seq 13993 df-fac 14259 |
This theorem is referenced by: fac4 14266 4bc2eq6 14314 ef4p 16083 ef01bndlem 16154 |
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